Construction of 5 Foot Vertical Wind Tunnel. The 5 Foot Vertical Wind Tunnel was built to study spinning characteristics of aircraft. It was an open throat tunnel capable of a maximum speed of 80 mph. NACA engineer Charles H. Zimmerman designed the tunnel starting in 1928. Construction was completed in December 1929. It was one of two tunnels which replaced the original Atmospheric Wind Tunnel (The other was the 7x10-Foot Wind Tunnel). In NACA TR 387 (p. 499), Carl Wenzinger and Thomas Harris report that "the tunnel passages are constructed of 1/8-inch sheet iron, stiffened with angle iron and bolted together at the corners. The over-all dimensions are: Height 31 feet 2 inches; length, 20 feet 3 inches; width, 10 feet 3 inches.